1. Field of the Invention
The present invention relates to an information processing apparatus for connecting a plurality of node apparatuses by a common transmission line and for transmitting information and, more particularly, to an information processing apparatus for executing parallel calculations and an arbitration method in such an information processing apparatus.
2. Related Background Art
Hitherto, as an arbitration method of using transmission lines in a parallel calculation system constructed by connecting a plurality of nodes, a method of detecting a collision in the transmission line, a method of additionally arranging an arbiter and giving a permission on the basis of a request order in accordance with use requests or fixed priorities, a method of allocating a use time of the transmission line to each node every predetermined time, and the like exist.
In the above conventional examples, according to the method of detecting a collision in the transmission line, there is a drawback such that processes and apparatuses such as monitoring means of use situations of the transmission lines by other nodes, interval management until a request is again made after a collision was detected, and the like are complicated.
According to the method of additionally arranging an arbiter and giving a permission on the basis of the request order in accordance with the use requests or the fixed priorities, in the case where after the arbiter received a notification indicative of the end of a data transfer that is at present being executed, a long time is needed to transmit a use permission for a node to which the use of the transmission line is subsequently permitted, there is a problem such that a period of time during which the data transfer is not executed after completion of the present data transfer exists, so that a use efficiency of the transmission line is deteriorated. According to the method of allocating a right to use the transmission line to each node every predetermined time, when data of a variable length is transferred, it is necessary to divide long data and transmit the divided data.